Gear shift control system

ABSTRACT

An electro-mechanical system is utilized to control shifting of gears of the transmission of a vehicle driven by an internal combustion engine. Shifting is responsive to torque input and output of fluid torque converters or fluid couplings, and vehicle speed. The system contemplates the use of speed sensors connected to various power transmitting shafts which develop electric signals having a magnitude of current or voltage fed to a computer programmed in accordance with a predetermined formula whereby output torque of the fluid drive is derived and in subsequent conjunction with an electric signal having voltage or current in magnitude proportional to vehicle speed effects control of valves which actuate the gear shifting mechanisms. The programming of the computer is on the basis of an equation such that comparative input and output speeds of fluid torque converters or couplings, in the form of proportional electrical magnitudes, is processed by the computer to an electrical output signal proportional to output torque of the converter or coupling.

United States Patent [1 1 1 3,710,647 Dach et al. [451 Jan. 16, 1973 54GEAR SHIFT CONTROL SYSTEM 3,324,140 6/1967 Lewis et a1. ..74/866Inventors: Hansjiirg Bach, Friedrichshakm 3,572,168 3/1971 Shrraretal..74/752A X Giinter Gackstetter, Langenargen, both of Germany [73]Assignee: Zahnradfabrik Friedrichshaien AG,

' Friedrichshafen, Postfach, Germany [22] Filed: Aug. 3, 1970 [21] Appl.No.: 60,387

[30] Foreign Application Priority Data Aug. 5, 1969 Germany ..P 19 39691.9

[52] US. Cl ..74/73l, 74/866 [51] Int. Cl. ..F16h 47/00, B60k 21/00 [58]Field of Search ..74/73l, 866

[56] References-Cited UNITED STATES PATENTS 3,448,640 6/1969 Nelson..74/866 3,416,393 12/1968 Hattori 2,484,01 1 10/1949 Brunken et al.2,499,128 2/ 1950 Brunken 2,529,129 11/1950 Blair 3,007,351 11/1961Hilpert 3,182,778 5/1965 Driischel 3,073,179 1} 1963 'Christenson..74/73l X Primary Examiner-Leonard H. Gerin Attorney-Zalkind, Home &Shuster [57] ABSTRACT An electro-mechanical system is utilized tocontrol shifting of gears of the transmission of a vehicle driven by aninternal combustion engine. Shifting is responsive to torque input andoutput of fluid torque converters 0r fluid couplings, and vehicle speed.The system contemplates the use of speed sensors connected to variouspower transmitting shafts which develop electric signals having amagnitude of current or voltage fed to a computer programmed inaccordance with a predetermined formula whereby output torque of thefluid drive is derived and in subsequent conjunction with an electricsignal having voltage or current in magnitude proportional to vehiclespeed effects control of valves which actuate the gear shiftingmechanisms. The programming of the computer is on the basis of anequation such that comparative input and output speeds of fluid torqueconverters or couplings, in the form of proportional electricalmagnitudes, is processed by the computer to an electrical output signalproportional to output torque of the converter or coupling.

14 Claims, 3 Drawing Figures V PATENTEDJAn 16 I973 SHEET 2 BF 2 Fig.3

IN VEN TORS Hansjb'rg Dach Gllinter Gdcksfelter ATTORNEY GEAR smr'rCONTROL SYSTEM In prior art devices automatic transmission control hasbeen effected as a function of speed of the vehicle and engine load.Further, various expedients have been used for generating a fluidpressure to shift gears, such pressures being adapted to engine torqueor to the drive train. This pressure is proportional to the throttlevalve setting, or a load setting, or intake pressure, or by combiningsome manifestation of load in terms of pressure with some manifestationof vehicle speed in terms of pressure, for the purpose of developing apressure which is supposed tobe proportional to the engine torque ormore strictly the torque rotating the impeller of a torque converter ora fluid coupling. However, such prior art systems, (e.g., U.S. Pat. Nos.2,788,678 and 2,932,990) taken in any form or combination of componentsproduce only a coarse approximation of the converter or fluid couplinginput torque and a mismatch of input power and load requirement results.In the case of diesel engines such systems are not feasible, the presentsystem is.

Likewise in prior art systems pressures are developed approximatelyproportional to the driving torque which must be raised to substantiallyhigher pressures after the shifting of gears but there is no change oftorque in thetorque converter required to bring it to the point ofhighest torque conversion. Accordingly, a pump is required to develop aseldom used pressure at the time of needed maximum torque conversion.

The present invention seeks to overcome the disadvantages of the priorart namely poor correspondence of torque in the gearing with actualcontrol conditions needed for accurate shifting control and therebyavoids large friction clutches or brakes, and supplemental devices, inthe transmission ultimately needed to effect smooth shifting.

Briefly, the invention provides a system wherein a computer determinesan electrical output signal in magnitude based on the drive torque,driven torque, and to the ratio of the driven and drive torques of thefluid drive. Such computer output signal of a particular magnitude isdetermined from electrical signals which are in magnitude proportionalto converter or fluid coupling drive speed and driven speed, wherein thecharacterizing data of the particular fluid drive is programmed into thecomputer. The computer output is processed through suitable controldevices involving further electrical signals of a magnitude proportionalto vehicle speed whereby an ultimate control signal is provided foractuation of solenoid valves in a hydraulic system wherein a pressureproportionalto the torque output of the fluid drive becomes availablefor shifting of gears, or solenoid controlled pressure operated valves.

An essentialadvantage of the invention as compared with the prior artsystems which utilize motor torque for developing gear shiftingpressuresproportional to load is that in the present invention suchactuatingpressure is not proportional to the engine torque but rather to theoutput torque of the fluid drive and determined by a computer forinstant output signal in proportion to such output torque.

A detailed description of the invention now follows in conjunction withthe appended drawing in which:

FIG. 1 is a diagrammatic illustration of a system utilizing a fluidcoupling;

FIG. 2 is a diagrammatic illustration of a system using a torqueconverter;

FIG. 3 is a diagrammatic illustration of a modified system using atorque converter.

Referring to FIG. 1, the diagram depicts engine 1 connected by means ofan output shaft 2 with the impeller P of the fluid coupling K having theturbine T connected by shaft 3 to a gear train or mechanism in gear box4. A pressure controller valve 13 is connected to an oil pump 14 by apressure conduit 15, the oil pump being mounted directly on engineoutput shaft 2. Valve 13 is a solenoid controlled pressure operated typeof valve. Also mounted on the shaft 2 is a sensor 8 which develops anelectrical signal proportional to the drive speed n, of the fluidcoupling K. Such signal may be a voltage or current which is an analogueof the engine speed which drives the coupling K and can be effectedeither by an electrical generator or a speed responsive reostat or byany other well known device. The signal proportional-to the drive speedn is applied as an input via electrical connection 20 to a computer 9.In a similar manner a sensor 7 on shaft 3 sends an input electricalsignal via electrical connection 21 to computer 9, a signal which isproportional to the driven speed n, to the coupling K.

A further sensor 6 on the gear output shaft 5 provides an electricalsignal having a magnitude proportional to the vehicle travel speed V,such signal being conducted via connection 23 to an electrical controldevice 10, comprising a switch system.

The computer is programmed in accordance with the formula:

where M is the output torque of fluid drive K, M is the input torque atthe speed n l U/min (l rpm) and u is the conversion factor for thespecific fluid drive. Torques can be in any convenient units.

As can be seen the electrical magnitudes of input to v the fluidconverter are dependent on the ratio of the output and input speeds (n/n wherein a constant p. for any specific converter or fluid coupling isa factor, all as programmed into the computer 9. The computer output isan electrical signal of magnitude proportional to output torque M Theelectrical signal magnitude at the computer output actuates or controlsvalve 13 via electrical connection 22. The output also is transmitted tothe electrical control device 10 via connection 24. The speed sensor 6also transmits a voltage via line 23 to the control device 10.

Pressure from pump 14 is thus controlled at valve 13 proportional to thetorque output M ofthe coupling K and such pressure, either hydraulic orpneumatic, is conducted by conduits l6 and 17 to respective solenoidvalves 11 and 12. The valves 1] and 12 are independently controlled byoutput signals from the control device 10 via respective electricalconnections 25 and 26.

Accordingly, depending upon output signals from control device 10, thevalves 11 and 12 are energized for effecting shifting of gears in thegear box 4 by application of brakes, clutches, and the like, in aconventional manner. Valves 11 and 12 are solenoid controlled pressureoperated valves and control the pressure for power operation of gearshifting apparatus in the gear box, all in a conventional manner.

The embodiment shown in FIG. 2 utilizes a torque converter G, andreference characters in FIG. 2 correspond as to like components to thoseheretofore described in FIG. 1, except as noted below. Thus, in FIG. 2there is no direct sensing of the speed 11;, the output speed of theconverter, it being noted that there is no sensor 7 in FIG. 2 as thereis in FIG. 1. However, the output speed of the converter is derived as afunction of the vehicle speed sensed by the sensor 6 wherein theelectrical output signal from that sensor is fed to the control device10 and such control device has an output connection 28 to the computer9. Such derivation of an output signal for n; occurs in the controldevice 10 and, accordingly, the output signal in connection 28 to thecomputer 9 is essentially the same signal which the computer 9 in FIG. 1receives from the sensor 7 via connection 21.

Accordingly, operation of the modification of FIG. 2 operates as setforth for FIG. 1, except for n being indirectly provided as anelectrical signal to the computer input.

In the form of the invention shown in FIG. 3, a torque converter G isagain utilized and most components shown are similar to those shown inFIG. 2 with, however, certain exceptions. In FIG. 3 the engine 31 has acomponent 48 which sends a signal frequency proportional to engine rpm nvia line 50 to computer 39 while a signal proportional to engine torqueM goes to the computer via connection 5]. The output speed In of theconverter G is determined as in the embodiment of FIG. 2. Also, ondriven shaft 35 there is a sensor 36 which sends an electrical signalproportional to vehicle speed V via the line 53 to the electricalcontrol device 40. The electrical control device receiving such signaland being responsive to the gear shift setting in the gear box 34generates an output signal which passes to computer 39 via connection57, such output signal from control device 40 being proportional to theoutput speed n of the converter output shaft 33. The output of computer39 is connected via electrical connection 52 to control valve 43 andalso to the control device 40. The control device 40 is thus conditionedto energize valves 41 and 42 via respective electrical connections 53and 56 in the output of the control device to effect gear shifting ingear box 34 in accordance with signals received via connections 53 and54.

Pressure for the valves comes from pump 44 mounted on the converterinput shaft 32 and connected via a conduit 45 to control valve 43 andthence via lines 46 and 47 to the respective valves 41 and 42. Thepressure in valve 43 is a function of the value of the torque output Mof converter G, similarly to valve 13, FIGS. 1 and 2.

In contrast to the forms of the invention in FIGS. 1 and 2 themodification of FIG. 3 utilizes a torque output M determined from enginetorque M which is determinable in various ways as by throttle valvesetting or intake manifold pressure or from some other variable controlor characteristic of the engine. In the modification of FIG. 3 thecomputer 40 is programmed in accordance with the equation M M, p. n)/n,, and such computer is less expensive than that shown in theprevious modifications.

The form shown in FIG. 3 is intended for fuel injection engines nowcoming into vogue, no carburetor being used. The component 48 is anengine driven pulse transmitter having a signal frequency proportionalto engine rpm.

The signal for motor torque M via line 51 is a function of intakepressure effected in a known manner by an inductive measuring sensor.

Regarding the preceding descriptions, it will be understood that thebasis concept of shift control is based on torques and vehicle speed.The hydraulic and electrical components may be selected to suit variousapplications, e.g., solenoid operated or pressure operated solenoidcontrolled valves may be used. Any suitable computer is usable made inaccordance with well known principles for effecting an output signalbased on programming for a signal proportional to torque output of thefluid drive. Voltage generators have been found suitable for rpmmeasurement of n n and V, i.e., the sensors 6, 7, 8. Alternatively,pulse transmitters are usable, where pulse frequency is proportional torpm. In fact, pulsing produced by cylinder firing is usable, i.e., thefiring of the spark plugs.

What is claimed is:

l. A system for changing gear ratios in a gear transmission comprising afluid drive for driving said transmission from an engine; means foreffecting electrical input signals proportional to input speeds andoutput speeds of said fluid drive; a computer programmed in accordancewith characteristics of said fluid drive to derive output electricalsignals proportional to output torque of said fluid drive in response tosaid input signals; and means for applying said output signals to a gearchange mechanism of said transmission to effect selective shifting inconjunction with electrical signals proportional to the output speed ofsaid transmission.

2. A system as set forth in claim 1, wherein said computer is programmedin accordance with the equation where M is the output torque of thefluid drive to be derived as said output signal; M, is the input torqueto the fluid drive, n is the input speed of the fluid drive, n is theoutput speed of the fluid drive and p. is a constant for the specificfluid drive dependent upon the characteristics thereof.

3. A system as set forth in claim I, wherein said computer is programmedin accordance with the equation where M is the output torque of thefluid drive derived by the computer, M is the torque of the engine, p.is a constant dependent upon characteristics of the fluid drive, n, isthe input speed of the fluid drive and n is the output speed ofthe fluiddrive.

4. A system as set forth in claim I, wherein said fluid drive is a fluidcoupling.

5. A system as set forth in claim 1, wherein said last mentioned meanscomprise an output shaft of said transmission and means on said shaftresponsive to speed thereof for transmitting a signal representative ofthe .value of such speed, said last mentioned means being effective toprovide an input signal to said computer proportional to the outputspeed of said fluid drive from the electrical signal proportional to thespeed of said transmission shaft in conjunction with the specific speedsetting of the gear shifting mechanism at that time.

6. A system as set forth in claim 1, including said fluid drive havingan input shaft and an output shaft and speed responsive means on each ofsaid shafts for effecting said electric signals proportional to theinput and output speeds of said fluid drive.

7. A system as set forth in claim 3,wherein said fluid drive is a torqueconverter.

8. A system as set forth in claim 7, wherein the factor (M for motortorque is derived as a function of engine intake pressure and the factorfor input speed (m) of the fluid drive is provided by electrical impulsetakeoff from a fuel injection system wherein frequency of pulsesprovided is proportional to input speed (n 9. A method of changing gearratios in a vehicle transmission having a fluid transmitter and gearingwhich comprises measuring input speed to the fluid transmitter;determining output torque of the fluid transmitter from the measuredinput speed and the operating characteristics of the fluid transmitter;ascertaining a value of speed of said vehicle, and shifting the gearingto a gear ratio selected on the basis of occurrence of a predeterminedvalue of said torque in conjunction with predetermined vehicle speed.

10. In combination with a transmission having a fluid transmitterdriving change speed gearing, drive ratio establishing means connectedto the gearing, a source of pressurized operating fluid connected tosaid drive ratio establishing means, signal controlled meansconnected tothe drive ratio establishing means, signal generating means connected tothe fluid transmitter for measuring speed, computer means connected tothe signal generating means and programmed to process speed informationin accordance with operating data associated with said fluid transmitterfor producing an output signal proportional to the output torque of thefluid transmitter, and pressure control means connected to the computermeans for varying the pressure of the operating fluid in proportion tothe output torque of the fluid transmitter.

l l. The combination of claim 10 including means for supplying saidoutput signal of the computer means to 'the signal controlled means forchanging the drive ratio as a function of the output torque of the fluidtransmitter.

12. The combination of claim 11 wherein the speed information processedby the computer means includes input and output speeds of the fluidtransmitter measured by the signal generating means.

13. The combination of claim 10 wherein the speed information processedby the computer means includes input and output speeds of the fluidtransmitter measured by the signal generating means.

147 The combination of claim 10 wherein the speed information processedby the computer means includes the input speed of the fluid transmittermeasured by the signal generating means and an output speed valuedeveloped by the signal controlled means in response to output speed ofthe gearing measured by the signal generating means.

1. A system for changing gear ratios in a gear transmission comprising afluid drive for driving said transmission from an engine; means foreffecting electrical input signals proportional to input speeds andoutput speeds of said fluid drive; a computer programmed in accordancewith characteristics of said fluid drive to derive output electricalsignals proportional to output torque of said fluid drive in response tosaid input signals; and means for applying said output signals to a gearchange mechanism of said transmission to effect selective shifting inconjunction with electrical signals proportional to the output speed ofsaid transmission.
 2. A system as set forth in claim 1, wherein saidcomputer is programmed in accordance with the equation M2 Mp (n2 )/n1 .Mu ( n2 )/n1 . n12 where M2 is the output torque of the fluid drive tobe derived as said output signal; Mp is the input torque to the fluiddrive, n1 is the input speed of the fluid drive, n2 is the output speedof the fluid drive and Mu is a constant for the specific fluid drivedependent upon the characteristics thereof.
 3. A system as set forth inclaim 1, wherein said computer is programmed in accordance with theequation M2 M1 . Mu ( n2 )/n1 where M2 is the output torque of the fluiddrive derived by the computer, M1 is the torque of the engine, Mu is aconstant dependent upon characteristics of the fluid drive, n1 is theinput speed of the fluid drive and n2 is the output speed of the fluiddrive.
 4. A system as set forth in claim 1, wherein said fluid drive isa fluid coupling.
 5. A system as set forth in claim 1, wherein said lastmentioned means comprise an output shaft of said transmission and meanson said shaft responsive to speed thereof for transmitting a signalrepresentative of the value of such speed, said last mentioned meansbeing effective to provide an input signal to said computer proportionalto the output speed of said fluid drive from the electrical signalproportional to the speed of said transmission shaft in conjunction withthe specific speed setting of the gear shifting mechanism at that time.6. A system as set forth in claim 1, including said fluid drive havingan input shaft and an output shaft and speed responsive means on each ofsaid shaftS for effecting said electric signals proportional to theinput and output speeds of said fluid drive.
 7. A system as set forth inclaim 3,wherein said fluid drive is a torque converter.
 8. A system asset forth in claim 7, wherein the factor (M1) for motor torque isderived as a function of engine intake pressure and the factor for inputspeed (n1) of the fluid drive is provided by electrical impulse takeofffrom a fuel injection system wherein frequency of pulses provided isproportional to input speed (n1).
 9. A method of changing gear ratios ina vehicle transmission having a fluid transmitter and gearing whichcomprises measuring input speed to the fluid transmitter; determiningoutput torque of the fluid transmitter from the measured input speed andthe operating characteristics of the fluid transmitter; ascertaining avalue of speed of said vehicle, and shifting the gearing to a gear ratioselected on the basis of occurrence of a predetermined value of saidtorque in conjunction with predetermined vehicle speed.
 10. Incombination with a transmission having a fluid transmitter drivingchange speed gearing, drive ratio establishing means connected to thegearing, a source of pressurized operating fluid connected to said driveratio establishing means, signal controlled means connected to the driveratio establishing means, signal generating means connected to the fluidtransmitter for measuring speed, computer means connected to the signalgenerating means and programmed to process speed information inaccordance with operating data associated with said fluid transmitterfor producing an output signal proportional to the output torque of thefluid transmitter, and pressure control means connected to the computermeans for varying the pressure of the operating fluid in proportion tothe output torque of the fluid transmitter.
 11. The combination of claim10 including means for supplying said output signal of the computermeans to the signal controlled means for changing the drive ratio as afunction of the output torque of the fluid transmitter.
 12. Thecombination of claim 11 wherein the speed information processed by thecomputer means includes input and output speeds of the fluid transmittermeasured by the signal generating means.
 13. The combination of claim 10wherein the speed information processed by the computer means includesinput and output speeds of the fluid transmitter measured by the signalgenerating means.
 14. The combination of claim 10 wherein the speedinformation processed by the computer means includes the input speed ofthe fluid transmitter measured by the signal generating means and anoutput speed value developed by the signal controlled means in responseto output speed of the gearing measured by the signal generating means.